Relay.



E. H. JACOBS.

RELAY.

APPLICATION FILED FEB. 26. 1914,

Patented Aug. 7, 1917.

Fig.5.

CUR/751W Wj'TNESSES JNYENTUH j ERNEST E $0035, 1,1 f %v\ hi4 Jan/v firs ATTUHNEY.

UNITED STATES PATENT OFFICE.

ERNEST H. JACOBS. OF SCHENECTADY. NEW YORK. ASSIGNOR T0 GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK.

RLLAY.

Specification of Letters Patent.

Patent-ed Aug. 7, 1917.

fl '0 all whom it 'Hltlj/ concern.

Be it known that l. llusnsr ll. Jacons, a citizen of the linitcd States, residing at Schcneclmly, county of Sclwncetmly, State of New York, have invented certain new and useful Improvements in Relays, of which the following is a slu cilication.

My invention relates to elcctroresponsive protective devices which respond to abnormal conditions such as overload, and more particularly to relays, such as time limit relays.

In many forms of relays commonly used in which a movable member is actuated by some suitable electroresponsive device, certain characteristics are observed which are undesirable and in some respects disadvantageous. The force. exerted upon the movable member of the relay is not the same at all points of its travel; and this force is apt to increase with the increase in the overload or other abnormal condition on the circuit to such an extent that on extreme overloads the movable member responds in a very diflerent manner than is desired. On very heavy overloads the thrust of the movable member of the relay may be. so great that a retarding device, such as a bellows, is no longer able to control the movable memher and give the. desired time limit so that in many inverse time limit relays, in which the time of operation is intended to be an inverse function of the extent of the over load, the time setting is practically lost on very heavy overloads. Tn such cases and in many others it is desirable that the relay have characteristics different from those now commonly used.

The object of my invention is to provide a relay which has the desired characteristics and will retain those characteristics under practically all conditions of service, so that if, for example, a number of relays are. so connected that all will be affected by the same disturbance on the system and are set to operate in a definite sequence they will operate in that sequence even though the disturbance is very severe. Another object is to provide a time limit relay which will retain its time setting under all conditions. A further object is to provide an inverse time limit relay in which the time of action is very nearly inversely proportional over a wide range of current. A still further object is to make general improvements in the construction and operation of both time limit and instantaneous relays.

In carrying out my invention I so modify and vary the relation of the movable element to the actuating parts and so control the movable member by means responsive to abnormal conditions that the desired characteristics are obtained and retained over a wide. range of overload. In the preferred construction the movable member or armature is so proportioned and related to electromagnctic actuating and controlling means that forces calculated to secure the desired action are exerted upon the movable member in all of its positions and under practically all conditions of overload. In addition to proportioning the armature I may use a retarding or controlling winding for exerting upon the movable member or armature a controlling or modifying force which is so proportioned to the forces tending to move it into an operative position that the desired characteristics are obtained. The 'arious features of my invention are more fully described in the annexed specification and pointed out with particularity in the appended claims.

My invention will best be understood in connection with the accompanying drawing in which merely for purposes of illustration I have shown one of the various forms in which my invention may be embodied, and in which Figure 1 is a longitudinal section of a time limit relay embodying my invention: Fig. 2 is a diagram showing the characteristic curves of relays such as have been heretofore commonly used and of the relay embodying my invention: and Fig. 3 is a diagram illustrating another form of relay embodying my invention.

In the particular form of device shown in Fig. 1 the. tripping circuit of a circuit breaker or automatic switch is controlled by contacts 1 which cooperate with a movable bridging contact 2 moved into engagement with the contacts 1 by the action of the relay. l'f a time lag is desired. as in a time limit relay. the relative movement of the contacts 1 and '2 may be controlled by some suitable retarding device. such as the bellows 3, which is provided with an adjust able opening for permittin the escape of its contents at a rate dependent upon the pressure exerted upon the bellows. Tn the particular arrangement shown the bellows 3 retards the movement of the contact 2 through being connected to a sleeve 4 upon which the movable contact 2 is mounted. This sleeve in turn is engaged and actuated by a spring 5 strong enough to form a substantially rigid connection to the sleeve 4 but resilient enough to absorb any vibrations which may be caused in the movable members of the relay by alternating current.

The spring 5 and the sleeve 4, together with the bridging contact 2, are all moved by the movable member or armature of the relay. In the particular form of relay shown this movable member consists of a tapered plunger 7 having a cone shaped upper end 8. The upper end 8 of the plunger cooperates with a. tubular polepiece 9 having at its lower end a conical recess corresponding to the cone shaped upper end 8 of the tapered plunger 7. The polepiece 9 is set in. a framework 10 of iron or similar material which forms a substantially closed magnetic circuit and has a cross piece 11 of the same material in which there is an opening 12, through which the tapered part of the plunger extends. The plunger 7 is actuated by means of an actuating winding 13 mounted inside the framework 10 concentric with the core 7 and polepiece 9. The actuating winding may have a plurality of taps 13 for connecting more or less of the turns of the winding 13 in circuit.

, In accordance with my invention, the tapered plunger 7 with its cone shaped upper end 8 is so proportioned and related to the cross piece 11 and to the tubular polepiece 9 that as the plunger rises the air gap in the magnetic circuit of which the core forms a part decreases in such a manner that the magnetic pull is substantially the same in all positions of the plunger. As a result, the movement of the plunger along the axis of the actuating winding 13 in response to current flowing in that winding is not afiected or interfered with by a constantly decreasing air gap in the magnetic circuit. as in many types of solenoid relay heretofore used and its thrust is nearly uniform throughout its travel, although unless other modifications were made, its thrust would be much greater on heavy overloads than on light overloads. I further prefer to so proportion the plunger 7 that it becomes saturated when the amount of current through the relay or the actuating winding 13 reaches a predetermined limit. as, for example, three times the amount of current required to start the plunger. As aresult a very large overload on the main circuit does not cause a correspondingly great force to be exerted upon the plunger 7 by the winding 13, since this force does not increase directly proportional to the current after the plunger becomes saturated. The modification in the action of the winding 13 upon the plunger due to the shape and proportioning of the plunger. is of great value in securing the desired characteristics in any type of relay, and is especially useful in time limit relays, since upon very severe overloads the forces exerted upon the plunger of the usual solenoid type of relay become so great that the retarding device, such as the bellows 3, unable to control the movement of the plun ger unless some suitable provision is made to protect it against the excessive pressure exerted by the plunger.

The effect of the actuating winding 13 upon the movable member or plunger 7 is further modified and controlled by some suitable retarding or controlling means for exerting upon the plunger a force which is opposed to that exerted by the winding 13. This opposing force is preferably dependent upon conditions in the circuit to be controlled. In the particular form shown in Fig. 1 this retarding or controlling force is secured by means of a retarding coil 1t mounted in the lower part of the framework 10 to encircle the lower part of the plunger 7 and wound in the proper direction to exert a retarding force upon it. To increase the effectiveness of the retarding coil 14, an armature 15 may be secured to the lower end of the plunger in a position to assist the action of the coil in retarding the plunger. The retarding coil furthermore assists the actuating winding 13 in saturating the plunger, so that the plunger may be saturated at current densities much lower than would be possible if only the actuating winding 13 were present. By properly proportioning the retarding coil and its associated parts it is possible to vary as desired not only the degree of retardation but the value of current at which saturation of the plunger occurs. As a consequence of the coaction of all of the different elements of the relay the thrust exerted by the plunger is substantially constant over a very wide range of overload and the desired characteristics in action are secured over a very wide range of overload.

In Fig. 2 the full line curve 16 is the characteristic curve of a relay embodying my invention, while the dotted line is a similar characteristic curve of forms of relay heretofore commonly used for the same purose. As clearly appears from the curved dotted line 17, the relays commonly used operate much more quickly than they should during the first part of the curve. while a relay embodying my invention has a characteristic inverse time curve which is substantially a straight line.

In Fig. 3 I have illustrated diagrammatically a form of my invention in whi h each of the two cooperating windings is resp n sive to a condition on the circuit difierent llll from that to which the other winding re-.

connected to be responsive to current flowing in the circuit, while the retarding winding lat is connected so as to be responsive to the voltage on the circuit. This modification in connections of the relay is particularly advantageous where a number of relays connected in series in the same circuit must maintain their selective action in spite of very violent disturbances on the circuit. For example, a short circuit causes a heavy flow of current and a marked drop in voltage near the short circuit. Substantially the same amount of current flows through the actuating windings of all the relays connected to the circuit, but the retarding winding of that relay nearest the short circuit is energized less than of any other, consequently the first relay to operate is the one nearest the short circuit. The greater the distance between the relay and the short circuit the less the drop in voltage and the greater the retarding action of the winding 14, so a selective action is secured which makes it certain that the relays will operate one after the other, beginning with the relay closest to the short circuit. By proportioning and varying the parts of the relay in suitable ways the relay can be so designed that it Will not operate until predetermined conditions are present on the circuit, or until the appearance of predetermined. conditions to which the control winding is responsive. For example, each relay shown in Fig. 3 can be so proportioned that it will not operate until the voltage has dropped a predetermined amount, and consequently no effect is produced on these relays which are so far away from the short circuit that the drop in Voltage does not eX- ceed permissible limits.

My invention may be embodied in other forms than that shown and described, and I therefore do not limit my invention to the precise arrangement disclosed except in so far as it is limited by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is 1. A tripping relay comprising an actuating winding, an iron frame which surrounds said winding and forms part of the magnetic circuit thereof, and an armature mounted to move along the axis of said Winding and shaped to form air gaps between the ends of said armature and said frame, the ends of said armature being tapered differently from each other and so proportioned that as said armature moves toward trip-ping position one air gap increases and the other decreases at such a rate that the thrust of said armature remains substantially uniform throughout its travel.

2. A tripping relay comprising a cylindrical armature mounted to move longitudinally and tapered at each end, an actuating "winding mounted to encircle said armature,

and an iron frame which surrounds said winding and armature and cooperates with said armature to leave an air gap between each end of said armature and said frame, one end of said armature having a taper different from that of the other end, said ends being so shaped that as said armature moves toward tripping position said air gaps change relatively to each other in such a way that the thrust of the armature remains substantially uniform throughout its travel.

3. A tripping relay comprising a cylindrical plunger mounted to move longitudinally and tapered at each end, an actuating coil mounted to encircle said plunger, and an iron framewhich surrounds said coil and has a tapered recess to cooperate with one end of the plunger to form an air gap and also has in alinement with said recess an opening through which the other end of said plunger extends to form another air gap in the magnetic circuit of said coil, the ends of said plunger being so tapered that one air gap increases and the other decreases in such a manner that the thrust of said plunger remains substantially uniform throughout its travel in response to current in said coil.

4. A tripping relay comprising a longi tudinally movable magnetic member having a portion of maximum diameter near one end and tapered from said portion to ward both ends, an iron frame having portions shaped to coact with said tapered portions of said member and maintain in the magnetic circuit an air gap which varies with the movement of said member to maintain a substantially uniform thrust in all positions of said member. and an actuating winding mounted in said frame to encircle said member at said portion of maximum diameter.

Tn witness whereof. l have hereunto set my hand this 25th day of Februarv. 191i.

lVitnesses:

ELIZABETH B. Anomnom. HELEN Onronn. 

